Since the confirmation process to lead the U.S. Department of Housing and Urban Development left some uncertainty, San Antonio Mayor Julián Castro had remained mum about the future.

Julián Castro cracks a smile after he spoke about his confirmation at City Hall.

Credit Ryan Loyd / TPR News

But on Wednesday, a full Senate confirmation finally allowed the 39-year-old mayor, husband and father to let his guard down and talk candidly about his new role in Washington, D.C.

During a Wednesday afternoon news conference, Castro spoke with emotion and candor.

"It is, for me, bittersweet to say goodbye as mayor, but in the next couple of weeks, I will do that," he said softly before a packed room of journalists inside City Hall.

His perceived mood just may have been a glimpse into the mayor's feelings about the big job he's stepping into, although his confidence and carefully chosen words didn't falter.

Castro acknowledged that he will be the 16th secretary of HUD. He happens to come from a city that seems to foster national leaders. Henry Cisneros also served as HUD secretary during the Clinton administration, and he came from the exact seat Castro is leaving as mayor.

In a past interview with Cisneros about Castro, Cisneros said he would be meeting with the mayor about the job ahead. Asked about those conversations, Castro said he appreciated those talks.

"He's had some very good advice; from advice about the organization to thinking about the work that HUD does," Castro said. "I won't get into private conversations that we've had, but he's been very encouraging."

In the next few weeks, Castro will formally resign from his mayoral post once the 10 city council members pick an interim mayor from among themselves. He said he did not have any particular member in mind to take over the seat until next May's city council elections. He did say he's confident that the leadership in place will continue the momentum he started and work to keep projects going forward.

"No matter what job you're in, it's never about one person," Castro said. "It's always about a strong team effort, and the fact is that we have a very strong council. No matter what the issues are, that decision will be made in a well-thought-out, rational way, where the best interest of San Antonio is put first."

Castro received bi-partisan support on his confirmation before the full U.S. Senate. Texas Sen. Ted Cruz voted no, while the other in the Senate, John Cornyn, voted yes.

Castro said he watched the confirmation with his wife, Erika, and his daughter.

"And to explain to Carina that they were voting on daddy and we told her the other day that we might be moving," Castro said to laughter.

Castro estimated that he'll be sworn in within the next few days by President Obama.